The present invention relates generally to a gas turbine power plant having twin-shafts and provided with a closed circulation system for a working gas. A nuclear reactor, which is gas-cooled and that operates by a once-through flow serves as the source of heat for the working gas. The gas turbine power plant includes a compressor as well as gas turbine, each of which have one high-pressure section and one lower-pressure section. Each compressor section and each gas turbine section are located on a common shaft. At least one current generator is provided which is driven by one of the gas turbine sections.
A power plant of this type, in which the low-pressure sections of the compressor and the gas turbine are arranged on one shaft, and the high-pressure sections of the compressor and the gas turbine are arranged on the other shaft, leads to engineering problems in connection with a control of speed of the compressor and turbine if the source of heat is a gas-cooled nuclear reactor with a once-through flow operation. In the event of rapid changes in operating conditions, for example should a load cutoff occur, the reactor would be subjected to wide fluctuations in pressure which could destroy the reactor.
A power plant is known in which a high-pressure and a low-pressure section of a compressor as well as a gas turbine are combined together and are all arranged, together with a current generator, on a single shaft. A nuclear reactor, which serves as the source of heat is placed between the two gas turbine sections. Such as plant does not necessarily result in any operational problems but the plant can not be designed so that it will operate at maximum efficiency. Furthermore, the long machine unit requires several shaft bearings and complicated pipe connections and is particularly unsuitable for use within a preloaded concrete pressure vessle.
A cross-compound arrangement is also known for a powerplant wherein a low-pressure section of a gas turbine drives both a high-pressure section of a compressor as well as a current generator. A high-pressure section of the gas turbine drives a low-pressure section of the compressor. The known power plant designed in this manner is relatively complicated and does not offer any particularly significant operational advantages in comparison with a standard arrangement having twin-shafts.
Accordingly, it is an object of the present invention to provide a gas turbine power plant having twin-shafts with a gas-cooled nuclear reactor operating by a once-through flow of a working gas as the source of heat which will react properly under both stable as well as transient operating conditions. Such a power plant has satisfactory engineering characteristics with respect to regulating behavior, with any danger to the reactor resulting from pressure fluctuations within the working gas being eliminated.
The present invention satisfies this and other objects in that the power plant is arranged in the form of a cross-compound system. The reactor is provided between the high-pressure section and the low-pressure section of the gas turbine. The power plant is accordingly arranged so that a mean working gas pressure between the two turbine sections, and consequently the pressure within the reactor, will be at least substantially constant at full load, no-load as well as standstill operation of the plant.
A plant designed in this manner is independently stable and can be regulated like any other gas turbine plant, for example by varying the upper temperature of the process. Whether operating at full load, partial load or no load, the process-limiting pressures, which vary in accordance with the operating conditions, will have no effect on the mean pressure of the working gas. The mean pressure of the working gas is also the mean pressure within the reactor. If a return line from the high-pressure pipe to the intake manifold of the compressor is provided, the nuclear reactor of such a plant will therefore never be endangered, even in case of a load cut-off or a rapid circuit-breaking. The use of a pipe line by-passing both the high-pressure section of the gas turbine and the reactor will improved the static as well as the dynamic behavior of the plant under partial load.